lspeasy / server/src / RequestHandler
Type Alias: RequestHandler<Params, Result>
type RequestHandler<Params, Result> = (params, token, context) => Promise<Result> | Result;Defined in: packages/server/src/types.ts:206
Signature for LSP request handlers registered via LSPServer.onRequest.
Type Parameters
| Type Parameter | Default type | Description |
|---|---|---|
Params | unknown | The request params type, inferred from the method name. |
Result | unknown | The response result type, inferred from the method name. |
Parameters
| Parameter | Type |
|---|---|
params | Params |
token | Transport |
context | RequestContext |
Returns
Promise<Result> | Result
Remarks
Handlers are async by default — returning Promise<Result> is fine. Throw a ResponseError to send a structured JSON-RPC error response. Throw any other Error to send a generic -32603 InternalError response.
Check token.isCancellationRequested at async yield points to stop early when the client sends $/cancelRequest.
Never
NEVER call server.close() or server.shutdown() from inside a handler — the server is processing messages on the transport at that point, and closing the transport from within a handler causes a deadlock: the handler awaits the close, but the close waits for all handlers to finish.
NEVER mutate server capabilities inside a handler. Capabilities are negotiated once during initialize; changing them at runtime has no effect on the client, which cached the InitializeResult at startup.
Throws
ResponseError A structured JSON-RPC error (preferred for protocol errors).
Throws
Error Any Error subclass is converted to a -32603 InternalError response.
See
- NotificationHandler for the fire-and-forget counterpart.
- RequestContext for the third parameter shape.